My rear brakes lock up constantly. It doesn't matter how easy I am on the peddle. The ABS goes through it's test on start up. Afterwards, the light goes out. The vehicle sat for quite a long time. I pulled the rear drums and inspected for rust and brake shoe condition. There was no rust to be found and the shoes seemed to be in good shape. I've read on here about some shoes retaining moisture and causing the same thing. These 'seem' dry. I've also read that it could be the RABS. Is there any testing to determine if the RABS is definitely the problem other than by-passing it?Thanks for the help in advance.

 

Do you have the shoes on backwards? That will cause the problem you describe. The larger shoe should be on the rear.

 

I had exactly that problem on my `87 F250. Tried new shoes and no different. Eventually replaced the RABS module on the frame rail and problem solved.
As far as I know the only real test is to use a short length of brake line to join the two brake pipes at the RABS module and bypass it. Then, if there is no difference, you can connect it back into the system.

 

I say once you have it bypassed you're better off leaving it that way.

 

My 1995 250 did that when I first got it. One of the rear drums was out of adjustment. Really scary in the snow.

 

Could not agree more, may prevent other problems down the line.
Unfortunately that option was not open to me at the time.

 

The rear shoes are on correctly and adjusted correctly so it looks like I'm going to attempt to by-pass the RABS and see what happens.Thanks for all the help.

 

Not to sound like an amateur, but I'm not very knowledgable about brake systems. What is the RABS? I have a 93 F250 as well, so I think I might need this information someday.

 

I assumed Rear Antilock Brake System.

 

I have a 74 f250 and my rear passenger brake locks up with with the slightest touch on the brake.
The truck had been sitting for 14 years allnin Alaska and as you probab ly know we have harsh winters so who knows what is going on with them.
I'm getting ready to pull the tires off and take a look at them but was just wondering if anyone had any ideas on what I might ha e to look forward to before I tackle the project.
Are they drums all around or just in the rear?
Thanks for any input.